In some cases, an apparatus may exchange information with one or more peripheral devices. For example, a personal computer may be able to communicate with printers, keyboards, and video cameras via a Universal Serial Bus (USB) interface. Moreover, each device might be associated with a number of different endpoints. For example, a personal computer might receive an indication movement from one endpoint of a USB computer mouse and an indication of a computer mouse click from another endpoint of that device. Note that the USB interface lets devices be added to (and removed from) the apparatus as desired by a user. As a result, the actual number of attached devices and/or active endpoints being used are not known when the apparatus is being designed.
One approach to designing such an apparatus is to provide support for a maximum number of attached devices and/or associated endpoints that will be permitted. For example, if up to thirty two devices are allowed to be connected to the apparatus, and each device is allowed to have thirty two endpoints exchange information with the apparatus, support for up to a total of 1,024 endpoints would be provided (e.g., buffers, registers, and other associated hardware may be provided such that 1,024 endpoints can be simultaneously supported by the apparatus). Such an approach, however, can be inefficient, especially if the number of devices and/or endpoints that are typically used is substantially less than the maximum number.